Penn Plax Plantation Rubber Dumbell is very canine friendly. Each Dumbell is made of tough, elastic gum rubber and the ends have 'pimples' on them. The design makes it easy for your friend to pick up and play with, and the 'pimples' massage the gums while playing. Each Dumbell comes in assorted colors and is approx. 4 1/2" in length and has a bell inside.